Messages in this thread | | | Date | Wed, 12 Jan 2005 09:37:27 -0800 (PST) | From | Christoph Lameter <> | Subject | Re: page table lock patch V15 [0/7]: overview |
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On Wed, 12 Jan 2005, Christoph Hellwig wrote:
> On Wed, Jan 12, 2005 at 08:39:21AM -0800, Christoph Lameter wrote: > > The future is in higher and higher SMP counts since the chase for the > > higher clock frequency has ended. We will increasingly see multi-core > > cpus etc. Machines with higher CPU counts are becoming common in business. > > An they still are absolutely in the minority. In fact with multicore > cpus it becomes more and more important to be fast for SMP systtems with > a _small_ number of CPUs, while really larget CPUs will remain a small > nische for the forseeable future.
The benefits start to be significant pretty fast with even a few cpus on modern architectures:
Altix no patch: Gb Rep Threads User System Wall flt/cpu/s fault/wsec 1 10 1 0.107s 6.444s 6.055s100028.084 100006.622 1 10 2 0.121s 9.048s 4.082s 71468.414 135904.412 1 10 4 0.129s 10.185s 3.011s 63531.985 210146.600
w/patch Gb Rep Threads User System Wall flt/cpu/s fault/wsec 1 10 1 0.094s 6.116s 6.021s105517.039 105517.574 1 10 2 0.134s 6.998s 3.087s 91879.573 169079.712 1 10 4 0.095s 7.658s 2.043s 84519.939 268955.165
There is even a small benefit to the single thread case.
Its not the case that this patch only benefits systems with a large number of CPUs. Of course that is when the benefits results in performance gains by orders of magnitude.
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